1. Field of the Invention
The present invention relates to an electron emission display.
2. Description of Related Art
In general, electron emission elements are classified into those using hot cathodes as an electron emission source, and those using cold cathodes as the electron emission source. There are several types of cold cathode electron emission elements, including Field Emitter Array (FEA) elements, Surface Conduction Emitter (SCE) elements, Metal-Insulator-Metal (MIM) elements, and Metal-Insulator-Semiconductor (MIS) elements.
An FEA element includes electron emission regions, cathode electrodes, and gate electrodes. The cathode and gate electrodes are driving electrodes. The electron emission regions are formed by a material having a relatively low work function or a relatively large aspect ratio, such as a molybdenum-based material, a silicon-based material, and a carbon-based material, such as carbon nanotubes, graphite, and diamond-like carbon so that electrons can be effectively emitted when an electric field is applied thereto under a vacuum atmosphere (or vacuum state). When the electron emission regions are formed by the molybdenum-base material or the silicon-based material, they are formed as a pointed tip structure.
The electron emission elements are arrayed on a first substrate to establish an electron emission device. The electron emission device is combined with a second substrate, on which a light emission unit (having a phosphor layer, a black layer, and an anode electrode) is formed. The first and second substrates, the electron emission device, and the light emission unit establish an electron emission display.
In the conventional electron emission display, the first and second substrates facing each other are sealed together at their peripheries using a sealing member and the inner space between the first and second substrates is exhausted to form a vacuum envelope (or vacuum chamber). Here, the electron emission regions, the driving electrodes, and the phosphor layers are provided inside of the vacuum envelope. That is, the electron emission device (or unit) and the light emission unit are provided inside of the vacuum envelope. The vacuum envelope has an effective area where light is actually emitted to display an image, and a non-effective area where there is no light emission to display an image.
The sealing member may include frit bars. Alternatively, the sealing member may include a glass frame and adhesive layers having frit.
The frit bar is formed by a mixture of glass frit and organic compound through a protrusion molding process. The frit bars are disposed between the first and second substrates and the first and second substrates are adhered to each other as the frit bars are heated to a molten state at a high temperature in the sealing process.
Also, when the sealing member seals the first and second substrates together, the sealing member contacts the driving electrodes (cathode or gate electrodes) arranged on the non-effective area.
Here, portions of the driving electrodes, which contact the sealing member, are leads (or extreme ends) of the driving electrode included in the electron emission device (or unit) and extending from the effective area to the peripheries of the first and second substrates.
That is, the sealing member adheres the first and second substrates to each other while contacting directly the extreme ends of the driving electrodes, thereby forming the vacuum envelope. Here, although the frit of the sealing member is the insulation material, it has a relatively low insulation property and a high permittivity as compared with other insulation materials.
Therefore, when the electron emission display is driven and thus an electric current flows along a first driving electrode, e.g., a cathode electrode formed on the first substrate by applying a driving voltage to the first driving electrode, the current flows to a second driving electrodes adjacent to the first driving electrode through the frit, thereby interfering with electric potential of the second (or adjacent) driving electrode. This causes the distortion of the voltage of the adjacent driving electrode. Here, the first and second electrodes refer to two adjacent driving electrodes among a plurality of driving electrodes arranged on the first substrate in a stripe pattern.